Process and device for the in-line NIR measurement of pourable foodstuffs

Abstract

A new NIR measuring process and apparatus which can measure both floury commodities and whole kernels, and other constituents of pourable foodstuff products in-line. A large number of individual measurements are made with a measuring time per individual measurement of less than 100, preferably 50, milliseconds and these are statistically averaged by a computer. A rotating filter principle as well as the diode array principle can be used. For grain products, the protein, water and ash content can be determined with a high degree of accuracy. The measured values are directly usable, for the control and regulation of corresponding foodstuff parameters.

We claim: 
     
       1. A process for measuring the constituents of pourable food products utilizing light at NIR wavelengths comprising the steps of: directing a pourable food product in a continuous stream past an in-line measurement area;   projecting light over a range of NIR wavelengths onto said food product as it moves past said in-line measurement area, said light being reflected from said food product;   detecting the reflected light at a plurality of NIR wavelengths over said range of NIR wavelengths, for obtaining an in-line measurement of the reflected light at said plurality of wavelengths over said range, the step of detecting the reflected light over said range of NIR wavelengths occurring in a period of time not greater than 100 ms;   repeating said steps of projecting light onto said moving food product and detecting the reflected light over said range of NIR wavelengths a predetermined number of times to obtain a predetermined number of in-line measurements of the reflected light at said plurality of wavelengths over said range;   averaging the in-line measurements at corresponding wavelengths layer said range to obtain averaged values; and   determining the constituents of the food product based on the averaged values obtained and a calibration value.   
     
     
       2. A process as claimed in claim 1, wherein said in-line measurement area includes a window adjacent to the food-product stream, and the step of projecting light over a range of NIR wavelengths includes projecting said light onto said food product as it moves past said window; and wherein the step of directing the food product in a continuous stream includes moving the food product at a controlled rate by a screw conveyor. 
     
     
       3. A process as claimed in claim 1, wherein the food product comprises grain kernels, and comprising the additional step of correlating the rate of movement of the food product past said measurement area with the step of detecting the reflected light at a plurality of NIR wavelengths over said range of NIR wavelengths so that a single kernel moves less than 1/10 of its length during said step of detecting. 
     
     
       4. A process as claimed in claim 1, wherein said step of repeating is performed a minimum of thirty times, thereby obtaining a minimum of thirty in-line measurements of the reflected light at said plurality of wavelengths over said range. 
     
     
       5. A process as claimed in claim 1, wherein the step of directing a pourable food product in a continuous stream includes moving the food product in a compact, homogeneous stream. 
     
     
       6. A process as claimed in claim 1, wherein the step of detecting the reflected light over said range of NIR wavelengths occurs in a period of time not greater than 50 ms. 
     
     
       7. A process as claimed in claim 6, wherein the step of directing a food product in a continuous stream past the in-line measurement area includes moving the food product at a controlled rate. 
     
     
       8. A process as claimed in claim 1, wherein the step of detecting the reflected light at a plurality of NIR wavelengths over said range of NIR wavelengths occurs substantially simultaneously. 
     
     
       9. A process as claimed in claim 8, further comprising the step of separating the reflected light into said plurality of wavelengths over said range and directing said separated light to a diode array detector for measurement of the reflected light at said plurality of wavelengths. 
     
     
       10. A process as claimed in claim 1, wherein the step projecting light over a range of NIR wavelengths includes projecting light at a plurality of specific wavelengths sequentially so that the detection of the reflected light occurs sequentially for the plurality of NIR wavelengths over said range. 
     
     
       11. A process as claimed in claim 10, wherein the step of projecting light at a plurality of NIR wavelengths includes rotating a filter wheel in the path of a light beam, said filter wheel having a plurality of NIR filters spaced thereon to permit projection of light at said specific wavelengths as said filter wheel is rotated. 
     
     
       12. A process as claimed in claim 11, wherein said plurality of filters includes a minimum of six filters spaced around said wheel And wherein said step of rotating the filter wheel includes rotating the filter wheel at greater than 25 revolutions per second. 
     
     
       13. A process as claimed in claim 1, wherein the step of directing a food product past said measurement area includes directing the food product through a pipe in a continuous, in-line stream substantially normal to the light projected onto said food product. 
     
     
       14. A process as claimed in claim 13, wherein the step of directing a food product through a pipe includes diverting the food product through a bypass pipe and regulating the rate of movement of the food product through said bypass pipe past said measurement area. 
     
     
       15. Apparatus for measuring the constituents of a pourable food product comprising: a channel through which a pourable food product moves in a continuous stream;   an in-line measurement area located in said channel;   a NIR measuring device positioned adjacent to said in-line measurement area for the in-line measurement of the constituents of said pourable food product as said food product moves past said measurement area;   said NIR measuring device having means for projecting light onto said food product as it moves past said measurement area and for detecting reflected light at a plurality of NIR wavelengths over a preselected range of NIR wavelengths to provide a plurality of in-line measurements of the reflected light at said plurality of NIR wavelengths;   computer means for statistically averaging the plurality of measurements obtained and for determining the constituents of the food product; and   means for moving the pourable food product through said channel past said measurement area.   
     
     
       16. Apparatus as claimed in claim 15, wherein said means for detecting includes means for separating the reflected light into said plurality of wavelengths within said preselected range of NIR wavelengths, and a diode array detector for measuring the reflected light at said plurality of wavelengths. 
     
     
       17. Apparatus as claimed in claim 15, wherein said NIR measuring device provides a plurality of in-line measurements of the reflected light at said plurality of NIR wavelengths, the time of each in-line measurement being not greater than 50 ms. 
     
     
       18. Apparatus as claimed in claim 15, wherein said channel includes a pipe for carrying said pourable food product in a continuous stream, and said in-line measurement area includes a window in said pipe adjacent to the food-product stream through which said light is projected onto said food product. 
     
     
       19. Apparatus as claimed in claim 18, wherein said means for moving the pourable food product controls the rate of movement of said, food product through said pipe. 
     
     
       20. Apparatus as claimed in claim 19, wherein said means for moving,the pourable food product comprises a screw conveyor and a drive motor for said screw conveyor controlled by said computer means. 
     
     
       21. Apparatus as claimed in claim 18, wherein said NIR measuring device includes a light source, a rotatable filter wheel, and a plurality of NIR filters spaced thereon to permit projection of light at specific NIR wavelengths through said window as said filter wheel rotates. 
     
     
       22. Apparatus as claimed in claim 21, wherein said NIR measuring device further comprises a motor for driving said filter wheel at above twenty-five revolutions per second. 
     
     
       23. A process for measuring at NIR wavelengths at least one constituent of a flowable particulate substance during in-line processing of the substance, comprising: advancing said particulate substance in a continuous stream along a predetermined path during said in-line processing of said substance;   projecting light over a range of NIR wavelengths onto different sample zones of said particulate substance as they flow past a predetermined location in said path, said light being reflected from said sample zones;   detecting the reflected light from said sample zones of particulate substance at a plurality of NIR wavelengths over said range of NIR wavelengths, and measuring the reflected light at said plurality of wavelengths over said range, the detection of the reflected light: over this range of NIR wavelengths occurring in a period of time not greater than 100 ms;   repeating the steps of projecting light at said NIR wavelengths onto different sample zones of said particulate substance and detecting the light reflected therefrom until detection over said range of NIR wavelengths has occurred a minimum of thirty times, thereby obtaining a minimum of thirty repeated measurements of the reflected light at said plurality of wavelengths over said range;   obtaining the mean value of the measurements obtained; and   determining the value of at least one constituent of the flowable particulate substance during in-line processing using the mean value obtained.   
     
     
       24. A process as claimed in claim 23, wherein the step of detecting the reflected light over the range of NIR wavelengths occurs in a period of time not greater than 50 ms. 
     
     
       25. A process as claimed in claim 23, wherein said step of obtaining the mean value is performed statistically. 
     
     
       26. A process as claimed in claim 25, wherein the step of determining is performed using the mean value and a calibration value. 
     
     
       27. A process as claimed in claim 23, wherein the step of projecting light over a range of NIR wavelengths onto different sample zones includes projecting light at a plurality of specific NIR wavelengths sequentially, and the step of detecting the reflected light occurs sequentially for the plurality of specific NIR wavelengths over said range. 
     
     
       28. A process as claimed in claim 27, wherein the step of projecting light at a plurality of NIR wavelengths includes rotating a filter wheel in the path of a light beam, said filter wheel having a plurality of NIR filters spaced thereon to permit projection of light at said specific NIR wavelengths as said filter wheel is rotated, the range of NIR wavelengths being the range of wavelengths encompassed by the NIR filters in the filter wheel. 
     
     
       29. A process as claimed in claim 28, wherein said plurality of filters includes a minimum of six filters spaced around said wheel and wherein said step of rotating the filter wheel includes rotating the filter wheel at greater than 25 revolutions per second. 
     
     
       30. A process as claimed in claim 23, wherein said particulate substance comprises a foodstuff. 
     
     
       31. A process as claimed in claim 30, wherein the step of advancing said foodstuff in a continuous stream includes moving the foodstuff in a compact, homogeneous stream. 
     
     
       32. A process as claimed in claim 30 further comprising the step of determining the throughput of the foodstuff during in-line processing of the foodstuff. 
     
     
       33. A process as claimed in claim 30, wherein more than one constituent of a foodstuff is measured. 
     
     
       34. A process as claimed in claim 30, wherein said predetermined path includes a window adjacent to the stream of foodstuff, and the step of projecting light over a range of NIR wavelengths includes projecting said light onto different sample zones of said foodstuff as they flow past said window; and wherein the step of advancing said foodstuff in a continuous stream includes moving the foodstuff at a controlled rate so that each of the sample zones flows past said window at substantially the same speed. 
     
     
       35. A process as claimed in claim 34, wherein the foodstuff comprises grain kernels, and comprising the additional step of correlating the rate of movement of the grain kernels past said window with the step of detecting the reflected light at a plurality of NIR wavelengths over said range of NIR wavelengths so that a single kernel moves less than 1/10 of its length during said step of detecting. 
     
     
       36. A process as claimed in claim 30, wherein the step of advancing a foodstuff includes directing the foodstuff through a pipe in a continuous, in-line, compact, homogeneous stream substantially normal to the light projected onto said foodstuff. 
     
     
       37. A process as claimed in claim 36, wherein the step of directing of a foodstuff through a pipe includes diverting the foodstuff through a bypass pipe and regulating the rate of movement of the foodstuff through said bypass pipe. 
     
     
       38. A process as claimed in claim 30, wherein said measuring process is conducted at each of two, separate, in-line locations, one measuring process being conducted on unrefined foodstuff and the other measuring process being conducted on refined foodstuff. 
     
     
       39. A process as claimed in claim 38, wherein said unrefined foodstuff is unground grain and said refined foodstuff is flour.